end of life or afterlife? - aogexpo.com.au€¦ · subsea mudmat 40 m × 32 m, ~ 1000t (epstein...

5/03/2017

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End of life or afterlife?

Susan GourvenecUniversity of Western AustraliaOceans Institute, Centre for Offshore Foundation Systems, OFFshore Hub

23rd February 2017Australasian Oil and Gas Conference

Is it more rational to leave offshore infrastructure in situ after decommissioning?

Who cares?

Operators

Tourism operators

RegulatorsLocal

industryCommercial

fishers

Rec fishers Rec diversGeneral public

Who cares?

Leckie, White, Draper & Cheng 2016, ASCE J Pipeline Systems Engineering Practice

Why do we care?

Over 600 fields expected to cease production in the next 10 years across the Asia-Pacific WOOD MACKENZIE, 2016

Australia has a future liability USD $21bn over next 50 yearsNERA, 2016

NERA Oil and Gas Industry Competitive Assessment“Australia scored poorly in abandonment - below the world median and significantly below the world best, Norway”

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Local landscape

Expected operational life of selected Western Australian offshore oil and gas

projects (WAMSI 2015)

http://www.wamsi.org.au

Options

Gourvenec & White (2017)Conference on Maritime EnergyDecommissioning of Offshore Geotechnical Structures

Operational project

Complete removalPartial removal & relocation

Partial removal & in situ decomm Augmentation


Engineering• A solution can be found to most engineering challenges with sufficient

investment.

AllseasPioneering Spiritwww.allseas.com

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Engineering• A solution can be found to most engineering challenges with sufficient

investment. • But just because we can - should we?

Challenges, risks & costs of removal (even for relocation).

Challenges, risks & costs of disposal onshore, landfill or recycling.

Destruction/disruption of established ecosystem around infrastructure.

Image from: Decommissioning in the North Sea, Arup

Engineering

Asgard subsea compression unit75 m x 45 m 5000t

www.statoil.comPhoto: Elin A/Statoil

Engineering

Gorgon projectSubsea mudmat40 m × 32 m, ~ 1000t(Epstein & Abelenet2014, Subsea7)mcedd.com/wp-content/uploads/ Subsea%207%20-%20MCED%20 REP%20presentation%20-%20% 209%20April%202014%20-%20PvA.pdf

Engineering

• If cost and risk of engineered removal are to be eliminated – the alternativemust be demonstrated to be safe from an engineering and ecological perspective.

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Engineering

• BOD for the afterlife is different to that for the production life

H

V

MT

• e.g. subsea structure• Less stringent tolerances on differential movements• No risk from loss of containment (once cleaned and flushed)• Avoid dispersal of structure in large or small parts

Engineering

• BOD for the afterlife• Less stringent tolerance requirements on differential movements• No risk from loss of containment (once cleaned and flushed)• Avoid dispersal of structure in large or small parts

V

• Loading less onerous in afterlife – absence of operational loads

Engineering

• BOD for the afterlife• Less stringent tolerance requirements on differential movements• No risk from loss of containment (once cleaned and flushed)• Avoid dispersal of structure in large or small parts

• Loading less onerous in afterlife – absence of operational loads• Resistance may increase relative to design state due to marine growth, burial/

embedment and increased seabed strength.

su ↑V

Engineering

• Viewed through lens of removal - increased resistance increases the challenge• Viewed through lens of in situ decommissioning - increased resistance is beneficial.

Potential retrieval resistance, or stability for the afterlife, for a subsea mudmat at end of field life (B = 5 m, B/L = 0.5 and d/B = 0.2, su (kPa) = 1+ 1.5z)

Gourvenec & White (2017)Conference on Maritime Energy,

Decommissioning of Offshore Geotechnical Structures

In situ decommissioning of subsea structures

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Engineering

Gourvenec et al. (2017)Offshore Technology Conference,

HoustonA toolbox for optimizing geotechnical

design of subsea foundations

• Same research informs different decommissioning options

Engineering

• Pipe self-burial• Harder to retrieve from seabed• Less likely to float away or disperse in an afterlife and cause a hazard

Temporal changes in the seabed topography around a pipeline on the NWS (Scale compressed in the along-pipe axis) (Leckie et al., 2015a)

Engineering

• Augmentation – artificial reef modules

courtesy of Subcon Pty Ltd

http://www.famer.unsw.edu.au/research.html


Marine science

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Marine science

Dr Diane McLean, Oceans Institute, UWA

• Fish diversity and abundance on pipelines;• Variability in fish assemblages on

pipelines;• Pipeline habitats;• How are fish utilising pipelines; and• Whether pipelines attract or enhance fish

stocks.• Create scientific data to assist in

assessing the value of pipelines to fish and fisheries on the north-west shelf.

Marine science

Implications for what to do with the pipelines after decommissioning

Cou

rtesy

of D

r Dia

ne M

cLea

n

Marine science

Courtesy of Dr Diane McLean

Marine science

Courtesy of Dr Diane McLean

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• Demonstrated benefits of offshore oil and gas infrastructure as part of the marine ecosystem.

• Can it do more harm than good removing infrastructure?• What are the risks associated with leaving the infrastructure in situ?

Marine science

Short term Long term

Known benefits Unknown risks

Evidence base required to maximize benefits and minimize negative impacts.


Society

Society• Who might be affected by decision about what to do with offshore

infrastructure at the end of production life? • What are the concerns? • Can they be addressed?

Operators consider gains from better policy to be important; other stakeholders and community will not support shift in policy without evidence, and the current state of relevant evidence is vastly insufficient.

• A review of stakeholder issues and concerns about decommissioning of offshore oil and gas facilities in WA has been undertaken as part of the WAMSI Blueprint for Marine Science.

• More than 100 individuals and organizations consulted. • Fishers, tourism operators, consultants, oil and gas operators, State

and Commonwealth regulators, management agencies.

Society• Learning from other sectors

Interactions between user groups and policy makers Coastal communities

Marine archeology Experience of things left of the seafloor for a long time Insight into human interaction with oceans

Could offshore oil and gas infrastructure decommissioned in situ form part of our industrial heritage in the future?

A/Professor Julian CliftonSchool of Agriculture and Environment, and Oceans

Institute, UWA

Professor Alistair PatersonSchool of Archaeology and

Oceans Institute, UWA

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Economics Economics• How much does each decommissioning option cost? • Cost who?

• operator• tax-payer• local industry• general public• environment

• Financial and non-financial consequences need to be assessed• Multi-variate life-cycle modelling

• What are the opportunities in decommissioning?• What is the value of the industry – domestically and to export expertise?• What is the effect of decommissioning policy and capability on future

investment?

• Learning from other sectors e.g. Mine site reclamation

What are the costs and benefits to the nation of offshore decommissioning?

Economics

A/Professor Ben WhiteSchool of Agriculture and

Environment, UWA

A/Professor Michael BurtonSchool of Agriculture and

Environment, UWA


Law, policy and governance

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• Geneva convention on the Continental Shelf (1958) requires complete removal of disused marine infrastructure.

• United Nations Convention on the Law of the Sea states that decisions should take into account generally accepted international standards established … by the competent international organization.

• International Maritime Organisation (1989) allows structures to be left in place on a case-by-case basis and refers to new use or other reasonable justification for in situ disposal.

• Due consideration must have been given to• safety of navigation• rate of deterioration• risk of structural movement• environmental effects

• costs• technical feasibility and• risks of injury associated with removal.


• Who owns liability if oil and gas infrastructure is left in situ?

• Work being done in this area …

Prof. Erika Techera, UWALawyer & Director of

Oceans Institute

Prof. John ChandlerCo-Director of Centre for

Mining, Energy and Natural Resources Law, UWA


Back to the question … Decision framework

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Decision framework

Optimal solution

The answer?

Architecture/infrastructureOffshore environment

Ocean usersPublic

National and regional policy

Complete removalPartial removal & relocation

Partial removal & in situ decomm

Augmentation

Moving forward

Forum theme How the Australian subsea industry can adjust to the evolving market

Ensure robust and effective regulations that support the industry;

Collaborate and invest in industry-led research –develop next generation of equipment and technology;

Collaborate with other countries – learn from best practice;

Innovate solutions to reduce risk, time and cost of decommissioning;

Grow local workforce capability.

The opportunity and business rational is clear for Australia to invest and build the relevant capability before the wave of decommissioning activities commences.

Moving forward

Create the scientific evidence base, develop technology and develop and deliver a decision tool across all stakeholders and relevant disciplines.

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Moving forward

Get in touch!

• Call to action!

• What are your challenges facing the upcoming wave of offshore decommissioning?

• What are your ideas & products to contribute towards making Australia more competitive in offshore decommissioning?

Acknowledgements

• UWA Oceans Institute • Centre for Offshore Foundation Systems• OFFshore Hub

• NERA• WAMSI

• Australian Research Council

• Australian Oil and Gas Exhibition and Conference• Society for Underwater Technology, Subsea Energy Australia and

Subsea UK

End of life or afterlife?

Susan GourvenecUniversity of Western AustraliaOceans Institute, Centre for Offshore Foundation Systems, Offshore Hub

23rd February 2017Australasian Oil and Gas Conference


Further info

Bernadette Cullinane, Partner and National Oil and Gas Leader

Deloitte Australia

Conference & Exhibition Perth, 14-17 May 2017

“Decommissioning – the next Australian oil and gas boom?

http://www.oceans.uwa.edu.auhttp://www.theconversation.com

end of life or afterlife? - aogexpo.com.au€¦ · subsea mudmat 40 m × 32 m, ~ 1000t (epstein...

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